Mastitis is an inflammatory condition of the mammary gland. It may affect any species, but bovine mastitis is of the greatest economic importance.
Bovine mastitis is usually associated with one or more microorganisms such as Streptococcus agalactiae, Streptococcus dysgalactiae, Staphylococcus aureus, Aerobacter aerogenes, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis, Clostridium perfingens, and Corynebacterium pyogenes which invade the udder through the teat canal and produce inflammation of the milk-producing tissue causing the formation of scar tissue which, once formed, may cause a permanent reduction in the cow's milk production. An infection can also alter the composition, quantity, appearance and quality of the milk.
The etiology of mastitis makes control of the problem dependent upon the critical diagnosis of the specific microbial agent involved, the correction of faulty managerial practices and the judicious use of intramammary therapy.